Method for communicating data between locally networked heterogeneous processing systems and communication system using said method

ABSTRACT

A method for communicating data in an aircraft between at least a first data processing system and a second data processing system locally networked, each processing system being capable of executing at least one application, wherein the data to be exchanged are organized in messages, the aforementioned messages as well as the processing systems and the applications being defined in files stored in a backup unit connected to the network and accessible by the data processing systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/FR2007/050969 International Filing Date 20 Mar. 2007, whichdesignated the United States of America, and which InternationalApplication was published under PCT Article 21 (s) as WO Publication No.WO2007/107674 A2 and which claims priority from, and the benefit of,French Application No. 200650971 filed on 21 Mar. 2006, the disclosuresof which are incorporated herein by reference in their entireties.

The aspects of the disclosed embodiments relate to a method forcommunicating data between locally networked heterogeneous dataprocessing systems in which the configuration of the communications isstored in a memory linked to the network and accessible from eachprocessing system. The aspects of the disclosed embodiments also relateto a communication system using this method.

The disclosed embodiments can be used in the field of network datacommunication, in particular by an Ethernet network, with remote orlocal processing systems on the same machine. In particular, thedisclosed embodiments can be applied in the field of aeronautics, andespecially aeronautical simulation and data transmission on board anaircraft or intended to be installed on board an aircraft.

BACKGROUND

In the field of data communication, it is common practice to connectdifferent data processing systems together through a local network suchas an Ethernet network. This linkage by local network permits differentprocessing systems to exchange data between themselves with fullsecurity, in other words without external systems being able to accessthese data. In certain fields, and in particular in aeronautics, thesesystems are often installed little by little, depending on the needs andthe development of these needs. In general, each of these systems hasbeen installed or modified to solve one or more particular problems.

Consequently, each system is often set up in a particular context with ameans of communication that is suitable for it. In particular, in thefield of aeronautics, different systems such as computers, dataprocessing applications, simulators, etc. are made by differentmanufacturers at different times, and thus with different technicaldevelopment. These different systems are intended to be installed on thesame aircraft, for example in the case of data transmission on board anaircraft, or associated with one another, for example in the case inwhich simulators are coupled with aircraft computers. Each system isthus put in place with a means of communication that is suitable foritself and which depends on the type of data to be processed, on theeconomic context, and on the technical context of the period in whichthe system was installed. Thus, each system is studied initially to workby itself and to solve specific problems. However, some data can be usedin multiple processing systems. Also, by economizing material andprocessing time resources, it is common practice to link multipleprocessing systems to one another through a local network, of the typeof an Ethernet network, to form a single communication system alsocalled a communication network. Such a communication system thenprovides a global heterogeneous architecture.

Because of this heterogeneity of the processing systems, the networkingof these systems necessitates adaptation of each of the systems to themeans of communication to make the data comprehensible by each of thesystems capable of sending or receiving these data. In other words, anunadapted system could not understand the data transmitted from anothersystem. In the same way, the data sent by this system would beincomprehensible and accordingly unusable by the other systems in thenetwork. This adaptation of systems necessitates the installation ofmeans of translation that can translate data produced in the format ofone system into the format of another system.

It is therefore understood that the greater the number of systemsconnected to the network, the more complex it is to configure thesemeans of translation and the more time it takes to integrate thesemeans.

Besides, each time a new system is installed and connected to thenetwork, it is necessary to adapt the means of translation already inplace to adapt the new system to the communication ensemble. Thetranslation of the data format of the new system thus must beincorporated into the existing means of translation so that the datafrom this new system can be comprehensible by the systems already inplace on the network.

Furthermore, the maintenance of the communication system ensemble isdifficult and critical since each processing system requires differentmaintenance by different methods. Also, if a system is faltering at agiven time, it is impossible to substitute for this system anothersystem of the network to accomplish at least some of its processing,since each system has its own format.

Such a communication system with heterogeneous architecture thuspresents the drawbacks cited above, with the consequences that thisentails on its operating cost, which depends directly on the time toperfect the translation of the data and to search for the failures.

SUMMARY

The exact purpose of the disclosed embodiments is to remedy thedrawbacks of the techniques described above. To this end, the disclosedembodiments propose a method for communicating data between multipleprocessing systems in which the same data configuration is adaptable toall of the systems. To do this, the method of the disclosed embodimentspropose storing the base information relative to the data and to thetopology of the network in a simple, homogeneous, and unequivocal formin a central memory accessible by all of the processing systems. Thismethod thus proposes storing in memory all of the information necessaryfor all of the processing systems of the communication network in anidentical form, in a place accessible by each. The data are exchangedbetween the systems in the form of messages that have a uniqueconfiguration and that have a number of data limited to the strictminimum. These data permit the system receiving the message to retrievefrom the central memory all of the data corresponding to this message.

More precisely, the disclosed embodiments propose a method forcommunicating data between at least a first and a second data processingsystem connected to a local network, with each processing system beingable to execute at least one application. This method is characterizedby the fact that the data to be exchanged are organized into messages,with these messages and the processing systems and the applicationsbeing described in the files in memory in a backup unit connected to thenetwork and accessible from the data processing systems, so that thedata processing system receiving a message is able from data furnishedin the message to retrieve from the files of the backup unit the datathat are necessary for it.

The method of the disclosed embodiments can also comprise one or more ofthe following characteristics:

-   -   one of the files in memory is a machine file that has a list of        all of the processing systems with an address on the network for        each system, defining a topology of the network,    -   one of the files in memory is an application file that has a        list of all of the applications and of the systems on which each        application can be executed,    -   one of the files in memory is a message file that has all of the        data that can be exchanged, and the paths that can be utilized        between the applications to transmit these data,    -   one of the files in memory is a user file that has a name,    -   the machine file, the application file, and the message file are        files shared by all of the users,    -   the user file is specific for each user,    -   the files are in the XML format,    -   each message has at least three data fields,    -   a first field contains a message identifier, a second field        contains the length of the message data, and a third field        contains the parameters to be exchanged,    -   the communication network uniting the processing systems is an        Ethernet network.

The disclosed embodiments also relate to a data communication systemthat has a plurality of processing systems connected to a local network,characterized in that it has a memory unit comprising:

-   -   a message file describing all of the data that can be exchanged        on the network,    -   a machine file describing a topology of the communication        network with a list of all of the systems and of their        respective addresses on the network,    -   an application file defining all of the applications that can be        executed on the network with all of the data related to each        application.

The memory unit is centralized, installed on the network, and accessibleby all of the processing systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematically a communication network pursuant to thedisclosed embodiments.

FIG. 2 shows an example of a message exchanged in the communicationsystem of FIG. 1 that has the configuration of the method of thedisclosed embodiments.

FIG. 3 shows a table describing examples of types of parameters of amessage of FIG. 2.

FIGS. 4, 5, 6, and 7 show examples of files recorded in the centralizedmemory of the communication system of the disclosed embodiments.

FIGS. 8A and 8B show respectively an example of communication ofmessages in a communication system pursuant to the disclosedembodiments, and a table summarizing this exchange.

DETAILED DESCRIPTION

The disclosed embodiments relate to a data communication method, or acommunication protocol, that permits an exchange of homogeneous databetween multiple data processing systems connected through a localnetwork. These systems can be installed on board an aircraft; they canalso be on the ground, in particular when these systems are simulatorscoupled with airplane computers to validate said computers before thefirst flight. In the following description there will be discussion of acommunication protocol in an aircraft, with the understanding that italso relates to systems on the ground, relative to the aircraft. Thislocal network can be an Ethernet network or any other local networkfunctioning by means of a protocol for data transmission by packets. Thetransmission of data on the local network is accordingly accomplishedaccording to a standard transmission process such as that of theEthernet network or of the Internet network. The data are transmitted onthe network in the form of messages that have a particularconfiguration, described below.

The method of the disclosed embodiments consists of using a simple,unique, and homogeneous topology that permits describing all of the datauseful to data processing systems with the same configuration and ofrecording the definition of these data on a single and uniquecentralized memory, also called the memory unit. This memory unitfunctions using a known format such as the XML format. The XML format isa computer language designed to manage long and complex documents suchas those found in Intranet networks, and that lets the user select thetype of data that he wishes to consult.

The configuration of the communications can also be assigned at thelevel of each user, with coherence being assured by the protocol of thedisclosed embodiments.

According to the disclosed embodiments, the useful information to bestored in the memory unit concerns the identification of the users ofthe communication network, i.e. the applications executed by theprocessing systems of the network and the identification of thedifferent data to be exchanged. The disclosed embodiments also proposeidentifying the formatting and distribution mechanisms of the data ofeach processing system.

To do that, the method of the disclosed embodiments proposes to describeall of the data in files recorded in the centralized memory. Each fileunites the data relative to the same type of element, for example theprocessing systems, the applications, etc. In particular, in thepreferred embodiment of the disclosed embodiments, four files providefor defining all of the data useful to all of the processing systems. Asexplained in greater detail below, a first file, called the machinefile, describes the topology of the communication network with the listof all of the systems and their respective addresses on the network. Asecond file, called the application file, defines all of theapplications that can be executed on the network with all of the datarelative to each application. A third file, called the message file,describes all of the data that can be exchanged on the network with allof the information relative to these data. A fourth file, called theuser file, identifies all of the users of the network, i.e. the name ofeach application of the network.

An example of a communication network using the method of the disclosedembodiments is shown in FIG. 1. This communication network 1 hasmultiple data processing systems. These processing systems are distantfrom one another, or are located on one and the same machine. In theexample of FIG. 1, a system 111 is installed on a machine 11, a system101 and a system 102 are installed on a machine 10, a system 131 isinstalled on a machine 13, and a system 121 is installed in a machine12. These machines, for example, can be the on-board computer of anaircraft, a flight simulator, or any other computer permittingdetermination of the flight parameters of the aircraft.

These processing systems are connected to one another through a localnetwork. A memory unit 2 for all of the information useful for thesesystems is also connected to this network. The memory unit is a backupunit dedicated solely to the configuration of the data that can beutilized by the data processing systems. This memory unit as shown inFIG. 1 corresponds to the configuration of the communications. Thisrepresentation of the configuration of the communications is only oneexample. FIG. 1 is non-limiting with regard to the topology of thenetwork. The memory unit 2 has multiple files, for example the machinefile 21, the application file 22, the message file 23, and the user file24, described below in detail.

The particular characteristic of this memory unit 2 is to be backed uppermanently or quasi-permanently. All of the data processing systems ofthe network 1 have access to this memory unit 2. This memory unit thusconstitutes a centralized means for backing up data. This memory unit 2permits the assurance of prefect homogeneity of the communicationnetwork, since all of the data are described there in the same way.Thus, any processing system accessing data is certain to have the sameinformation as that received or transmitted by another system on thenetwork. This permits the communication network to be coherent since allof the necessary data are assembled in a single place with a uniqueconfiguration. The data can thus be understood in only a single andunique way by all of the processing systems of the network. Accordingly,no faulty interpretation is possible. The communication protocolpursuant to the disclosed embodiments is accordingly unequivocal.

An additional advantage of this centralized memory unit 2 is that eachmodification of data can be known by all of the processing systems. Themodification is made only in the file or files containing thisinformation and it is echoed to the systems when they search in thememory unit. In addition, if the method of the disclosed embodiments haschosen a conventional format such as the XML format, then theconfiguration of the network is open-ended in both the number of objectsand in attributes characterizing each object. It thus permits rapidintegration and coupling of a system since only the files of the memoryunit have to be modified during the integration of a new system. Theusers of the network do not see their communication interface evolvingin any case.

In this communication network according to the disclosed embodiments,the data are exchanged between the processing systems by means ofmessages circulating in the network. A message is a base element in thetransmission on the network. To assure homogeneity of the network, themessages all have a unique configuration, i.e. they all have the samefields, positioned in the same order.

FIG. 2 shows an example of a message that has a configuration conformingto the disclosed embodiments. This message has a first field ch1 calledthe identifying field and corresponding to the identification of themessage in question. It has a second field ch2 called the length fieldthat gives the size of the message expressed in octets. It has a thirdfield ch3 called the parameter field that contains all of the parametersor data to be transmitted on the network. Thus each message circulatingon the local network is identified by a unique number.

With the messages being the base elements exchanged between users, i.e.between the applications executed by the processing systems, eachmessage contains:

-   -   the identity of the message, with this identity being in the        form of a whole number,    -   the length of the message, which permits the user receiving the        message to retrieve the type of data transmitted,    -   the parameters, i.e. the data that have to be transmitted to        another user. The system receiving the message, or the receiving        user, is able from the information furnished in the message to        retrieve from the memory unit files the data that it needs. In        particular, from the length of the message the receiving system        is able to retrieve the type of data, and from the parameters of        the message it is able to determine the values of these data.

FIG. 3 shows in the form of a table some examples of types ofparameters, or types of data, that may be contained in a message. Thistable has a list of types with the length in octets that corresponds tothem. This is the value in octets that is transmitted in the message.Upon receiving a message, the receiving system looks in theconfiguration of the communications for the characteristics of themessage that it has just received based on the identity of the message(first field). It compares the length (second field) with thetheoretical length found in the configuration, for purposes ofverification of the good condition of the communications, and thendetects the collection of parameters that compose the message (thirdfield) to be able to provide for decoding. These parameters, forexample, can be a whole number, an octet, a real number, a table, or aparameter of variable size. In the case in which the elementary type isa parameter of variable size, the method of the disclosed embodimentsprovides for minimizing the bandwidth by transporting only what isstrictly necessary.

The advantage of transmitting the length is to reduce the size of themessage, which facilitates its transfer. Actually, reducing the size ofthe message to its strict minimum permits economizing the bandwidth andassuring a faster transmission of the message. Knowing the exact flowrates and volumes of data transported permits controlling the bandwidthand thus anticipating any congestion problems.

The configuration ensemble of the message just described permitslimiting the size of the messages to the strict minimum. Thus, eachmessage circulating on the network is reduced to its minimum, with thisminimum nevertheless being sufficient for the message to be understoodby the receiving system. It should be understood, however, that othermessage configurations can also be used.

As explained above, all of the data capable of being utilized in thecommunication network of the disclosed embodiments are defined andrecorded in a unique centralized memory unit, or distributed at thelevel of each actor. These data are distributed among multipleconfiguration files, with each file being associated with a particularfunction of a particular element of the network. The data are thusdissociated into multiple files, which facilitates the physicaldescription of the communication network, of the applications, and ofthe static and dynamic characteristics of the data.

In a preferred embodiment of the disclosed embodiments, the data aredistributed into four files, already cited above:

-   -   the machine file describes the topology of the network. An        example of this file is shown in FIG. 4. This file describes all        of the data and characteristics relative to each of the data        processing systems of the network. This file in particular lists        the machines on which the different systems are implanted. This        file also lists the addresses of these systems on the network,        under the address named IP. This machine file is shared by all        of the users, i.e. all of the applications can have access to it        from any processing system whatsoever of the network.    -   the application file identifies all of the applications capable        of being executed in the processing systems of the network. An        example of such a file is shown in FIG. 5. This application file        lists all of the applications of the network. For each        application, it describes the processing systems on which the        application can be executed. It also describes for each        application the links between the different parameters. This        links define the communication paths, called communication        channels. These channels are defined by name, by IP address, by        the type of formatting (endianness in English), and by their        port number in the UDP/TCP sense. The TCP and UDP ports are data        synchronization modes, respectively with or without a guarantee        that the arrival and the order of arrival of the data are        respected. This application file is shared by all of the users.    -   the message file identifies all of the data or parameters that        can be exchanged. An example of such a file is shown in FIG. 7.        This message file lists all of the messages, and for each        message it describes the type of message, the type of        communication, and the period of communication. The message file        also describes for each message the application emitting the        message, the application receiving the message, and the channels        to be utilized to go from the emitting application to the        receiving application. It also contains the identification of        the message and the length of the message to be transmitted.        Finally, it defines the parameters contained in each message and        the type and size of these parameters. The message file is a        file shared by all of the users.    -   the user file identifies the user itself, i.e. the application        in question. An example of such a user file is shown in FIG. 6.        This user file has the name of the application whose        communications have to be taken into account. This file permits        substituting a second user for a first user, simply by changing        the name of the user in said file. This user file is specific        for each user. It cannot be consulted by the other users.

FIGS. 8A and 8B show an example of a communication network pursuant tothe disclosed embodiments in which three data processing systems H1, H2,and H3 are connected by an Ethernet network. The system H1 and thesystem H3 use processors of the Little type. System H2 uses a processoroperating according to the Big type. The types Little and Big are twodifferent incompatible methods of representing data in memory. The H1system accommodates multiple applications, i.e. applications A1 and A2.The H2 system accommodates the application A3 and the H3 systemaccommodates the application A4.

Each of these applications uses a channel C to transmit its data on thenetwork. For example, application A1 transmits its messages M1 and M2via the channel C1 to the application A3, and its message M4 via thechannel C2 to the application A4. The application A3 transmits itsmessage M3 via the channel C4 to the application A1. The application A4transmits its message M6 via the channel C5 to the applications A2 andA1. The application A2 transmits its message M5 via the channel C3 tothe application A4.

Each channel C1, C2, C3, C4, or C5 is monitored via an IP address and aTCP or UDP port. Examples of addresses of these channels are notedbeneath each system H1, H2, and H3.

Message exchanges between the three systems H1, H2, and H3 aresummarized in the table of FIG. 8B. This table thus tabulates the datarelative to the different messages emitted on the local network, in thenetwork example of FIG. 8A. For example, the first message emissionlabeled 1 sends the message M1 from the application A1 via the channelC1 to the application A3 via the channel C4. The parameters transmittedby the message M1 are the parameter 132 and the parameter F64. Thisparameter F64 is a 64-bit real-type datum with 5 reals. The parameter132 is a 32-bit integer.

Each application and each message having previously been defined in thememory unit, a message exchanged between two processing systems takesthe formatting differences between the two systems directly into accountwithout the necessity of adaptation. Actually, the files describing thedata take the characteristics of each system into account, with theeffect that the system itself does not have to manage any formatting orunformatting; it simply has to receive the message and to look in thefile to which this message corresponds. The change of format istransparent. In the example of FIG. 8A, the change of format to changefrom a Little mode or to a Big mode (which are two different modes ofarranging data in memory), is transparent for the systems H1, H2, andH3.

1. Method for data communication in an aircraft between at least a firstdata processing system and a second data processing system connected ina local network, with each processing system being able to execute atleast one application, wherein the data to be exchanged are organizedinto messages, with these messages and the processing systems and theapplications being described in files in memory in a backup unitconnected to the network and accessible by the data processing systems,so that the data processing system receiving a message is able frominformation furnished in the message to retrieve in the backup unitfiles the data that are necessary for it.
 2. Method pursuant to claim 1,wherein one of the files in memory is a machine file that has a list ofall of the processing systems with an address on the network for eachsystem, defining a topology of the network.
 3. Method pursuant to claim1, wherein one of the files in memory is an application file that has alist of all of the applications and of the systems on which eachapplication can be executed.
 4. Method pursuant to claim 1, wherein oneof the files in memory is a message file that has all of the data thatcan be exchanged and the paths that can be utilized, between theapplications to transmit these data.
 5. Method pursuant to claim 1,wherein one of the files in memory is a user file that carries a name,6. Method pursuant to claim 1, wherein the machine file, the applicationfile, and the message file are files shared by all of the users. 7.Method pursuant to claim 5, wherein the user file is specific for eachuser.
 8. Method pursuant to claim 1, wherein the files are in the XMLformat.
 9. Method pursuant to claim 1, wherein each message has at leastthree data fields.
 10. Method pursuant to claim 9, wherein a first fieldcontains a message identifier, a second field contains a data length ofthe message, and a third field contains the parameters to be exchanged.11. Method pursuant to claim 1, wherein the communication networkjoining the processing systems is an Ethernet network.
 12. Datacommunication system comprising a plurality of processing systems joinedin a local network, having a memory unit comprising: a message filedescribing all of the data that can be exchanged on the network, amachine file describing a topology of the communication network with alist of all of the systems and their respective addresses on thenetwork, an application file defining all of the applications that canbe executed on the network with all of the information relative to eachapplication.
 13. Communication system pursuant to claim 12, wherein thememory unit is centralized, installed on the network, and accessible byall of the processing systems.
 14. Aircraft, comprising a system forimplementing the communication method pursuant to claim
 1. 15. Aircraft,comprising a communication system pursuant to claim 12.